Surveillance of Influenza-Like Diseases through a National
Computer Network -- France, 1984-1989

In France, national surveillance of influenza-like syndromes
has been continuous since November 1984 through the French
Communicable Diseases Computer Network (FCDN). This report
describes epidemics documented from 1984 to 1989 and emphasizes
the 1988-89 epidemic.

FCDN was initiated under the joint auspices of the Institut
National de la Sante et de la Recherche Medicale (comparable to
the National Institutes of Health in the United States) and the
Direction Generale de la Sante (the national department of
health). FCDN uses electronic communications to facilitate
collection, analysis, and redistribution of epidemiologic
information about communicable diseases (1,2). Notifiable disease
data collected by France's 96 regional departments of health are
forwarded to the national department of health, analyzed, and
redistributed to all users of the network through a weekly
electronic bulletin.

FCDN collects epidemiologic data from general practitioners who
volunteer to provide sentinel notification of epidemics. In
November 1984, 50 sentinel general practitioners (SGPs)
participated in FCDN; the number of participants has increased
steadily and, since January 1988, has included 550, or
approximately 1% of, French general practitioners. The SGPs were
selected to be demographically representative of all general
practitioners (i.e., by age, sex, geographic distribution, and
type of practice). SGPs use terminals or personal computers with
modems to report influenza-like syndromes and other selected
conditions (e.g., measles, mumps, and viral hepatitis) to FCDN's
host computer. SGPs can access the host computer 24 hours a day
but must access the computer at least once a week--even if they
have no cases to report. In particular, SGPs report the age, sex,
and vaccination status of patients meeting the World Health
Organization definition of influenza-like syndromes (i.e., a
sudden fever of greater than 39 C, myalgia, and respiratory
symptoms) (3). Estimates of the incidences of influenza-like
syndromes are determined by geographic regions and redistributed
on FCDN 4-10 days after the report of diagnosis.

From November 1984 through April 1989, a total of 89,705 cases
of influenza-like syndromes were reported. In the 1984-85,
1985-86, and 1986-87 epidemics, increased activity began in the
second half of December, peaked in early February, and ended by
mid-April (Figure 1). During the respective three periods,
maximal incidences were 12.7, 9.4, and 5.6 cases per 1000
residents. Although the 1987-88 epidemic began considerably later
(late February), the maximal estimated incidence was comparable
(5.8 cases per 1000).

In 1988-89, however, increased activity began in mid-November,
peaked at 18.3 cases per 1000 residents during the second week of
December, and ended in late January. In addition, the 1988-89
epidemic was characterized by a different distribution among age
groups (Figure 1)--predominating in persons aged 0-17 years and
affecting a smaller proportion of elderly persons than previous
epidemics. Among persons aged 5-17 years, the peak incidence was
31.4 cases per 1000, compared with 2.4 cases per 1000 persons
aged greater than or equal to 65 years. Thus, the 1988-89
epidemic occurred earlier, was of shorter duration, and affected
primarily younger age groups while sparing the elderly.

From 1984 to 1989, the French Reference Centers on Influenza
("France Nord" and "France Sud") provided weekly results of viral
isolates. For the 1984-85, 1985-86, and 1986-87 epidemics, most
influenza isolates were A(H3N2) and A(H1N1) viruses. In 1987-88,
influenza B virus was most frequently isolated. In 1988-89,
influenza A(H1N1) predominated, although sporadic A(H3N2)
activity occurred (4). Respiratory syncytial virus (RSV) was also
isolated during each of the five periods. The predominance of
illness reported in the 0-4-year age group (peak incidence: 23.5
cases per 1000 persons) may reflect RSV activity during the
1988-89 epidemic.
Reported by: J Menares, Ph Garnerin, AJ Valleron, Unite de
Recherches Biomathematiques et Biostatistiques de l'Institut
National de la Sante et de la Recherche Medicale, Universite
Paris 7, Paris. Influenza Br and Epidemiology Office, Div of
Viral and Rickettsial Diseases, Center for Infectious Diseases,
CDC.

Editorial Note

Editorial Note:

A major strength of the FCDN system for surveillance of
infectious diseases is the rapidity of the collection, analysis,
and distribution of data. The reports of influenza-like illness
from SGPs, combined with information on virus isolations provided
by the French Reference Centers, provide timely information for
physicians who need to make decisions each year about both the
administration of influenza vaccine and use of antiviral agents
that are effective only against type A influenza viruses. Rapid
diagnostic techniques to determine the type of influenza reported
by the SGPs would further enhance the usefulness of this
innovative system.

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